Delaying breakup and avoiding air entrainment in curtain coating using a two-layer liquid structure

Alireza Mohammad Karim, Wieslaw J. Suszynski, Saswati Pujari, Lorraine F. Francis, Marcio S. Carvalho

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Successful curtain coating is limited by two flow instabilities, the breakup of the liquid curtain below a critical flow rate and air entrainment above a maximum substrate speed. These limitations make thin film coating at high speed a great challenge. Previous work has shown that the curtain breakup can be delayed to lower flow rates if the flowing liquid has viscoelastic behavior. However, viscoelastic stresses near the dynamic contact line destabilize the flow in that region, leading to the onset of air entrainment at lower web speeds. We propose and experimentally validate the use of a two-layer curtain coating configuration, with a shear-thinning liquid as the bottom layer and a viscoelastic liquid as the top layer, that expands the processing window and enables thin coating at high speeds.

Original languageEnglish (US)
Article number115376
JournalChemical Engineering Science
Volume213
DOIs
StatePublished - Feb 23 2020

Keywords

  • Capillary hydrodynamics
  • Curtain coating
  • Liquid sheet breakup
  • Two-layer coating
  • Viscoelasticity

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